The softening of fabrics during a laundering operation has been a part of the scene for about 30 years, beginning in the era when synthetic detergents began replacing soaps to launder fabrics. As long as soap was used for laundering, the hard water soap film left on the fabric provided the lubrication needed for a pleasing fabric hand. With the advent of synthetic detergents the need for a fabric softener was established.
The original fabric softeners were aqueous dispersions of cationic quaternary ammonium compounds such as the di (hydrogenated tallow) dimethyl ammonium chlorides and were added to the rinse cycle of the laundering operation.
With further technological changes responsible for the wide growth in synthetic fabrics, coupled with the increased use of automatic laundry dryers in the home, the importance of the softening effects of fabric softeners diminished somewhat, but the ability to eliminate static build-up on fabric became increasingly important. It was learned that fabric softeners could assist in reducing or preventing static in laundered fabrics which led to the discovery that softeners could be applied in the dryer as well as in the washing machine. The addition of a fabric softener to the fabric in the laundry dryer seems to improve static control but is actually less efficient in softening the fabric in that dryer added fabric softener sheets transfer to the fabric load a significantly less amount of fabric softener as do the wash or rinse cycle added products. The softener that is transferred in the dryer is concentrated on the surface of the fabrics and the result is that the softening effects are minimized, although the anti-static effect is enhanced over that obtained through rinse cycle application. With the advent of the nonionic detergents, it was found that the cationic softeners could be incorporated into the wash cycle as well. It had been previously recognized that the addition of cationic fabric softeners along with anionic based detergents in the wash cycle, substantially reduced both the cleaning efficiency of the detergent and the efficiency of the fabric softener. Thus there exists a need for a composition that can be added to the wash cycle of the laundering operation and which provides both effective softening and anti-static control while maintaining detergent efficiency with a wide range of detergents that include built anionic based products.